1917] Lipman-Gericke : Smelter Wastes and Barley Growth 503 



the treatment of the soil, but such depression obtains almost 

 without exception in the second crop of the ZnSO^ series. In 

 other words, a very marked decrease in the number of tillers 

 results from the second ZnSO^ application to the greenhouse soil, 

 both absolutely and relatively speaking, in comparison with 

 either the untreated control pots or with the treated pots of the 

 copper series. Much better agreement between duplicate pots 

 with reference to tillering is noted in the second crop of the 

 ZnSO^ series than in the other series above described. 



In the case of the potash alum series, in the first crop the 

 results were very similar to those obtained in the corresponding 

 copper series except that tillering was not so markedlj^ stimu- 

 lated as in the latter. In the second crop, also, the results of 

 the potash alum series were not strikingly different as regards 

 tillering from those in the copper series. 



In the first crop of the FeSO^ and PbSO^ series no observa- 

 tions were made on tillering owing to the poor development of 

 plants and their prostrate mode of growth, which was especially 

 marked in the lead series. Observations on the amount of tiller- 

 ing produced in the second crop of the FeS04 series indicated 

 that the stimulating effect of the FeS04 on tillering was not 

 so great as that of either copper or potash alum, but greater 

 than that of zinc. 



In the third crops of all series scarcely any tillering was 

 observed, the plants producing for the most part single upright 

 stalks. It appears, therefore, that the stimulating effects of the 

 salts tested with respect to tillering are ephemeral in their 

 nature, but are more distinctly so with some salts than with 

 others. 



Height of Plants 

 In the second crop only, observations and measurements were 

 made of the average and total heights of plants produced in the 

 CuSO^, ZnSO^, FeSO^, and potash alum series. These indicated 

 definite increases in height of plants produced by certain concen- 

 trations of all the salts named, over those attained by the plants 

 in the untreated pots. The superior height of the plants was, 

 however, variously distributed through the series. Thus it was 



